First, a clarification about the naming of this fern genus. You'll frequently see two genus of almost identical sounding names: microsorum and mircosorium (with an "i" at the end). It's easy to wonder if these are two separate genus, considering after all that many plants known as microsorium are aquatic or semi-aquatic plants and frequently used in aquariums, whereas the few mentions of microsorum are terrestrial or epiphytic plants.

In fact, they are the same genus, with species that have adapted to various levels of water. The confusion arises from a century-old spelling error by the scientist who named the genus and has persisted every since. The M. pteropus, or Java fern, is the popular aquatic plant, while other Microsorum species are seen growing in the air. All of them are tropical plants, and like many ferns, require high levels of moisture and humidity to thrive. This article deals only with the Microsorum species that are grown as houseplants, not the aquatic species.

Growing Conditions:

Light: These are low light plants, which is an advantage for the indoor gardener. Of the species grown indoors, their preferred conditions range from shade to dappled shade. Do not expose to direct sunlight.
Water: All species of Microsorum are water lovers, with a high demand for both humidity and water in the growing media. In temperate climates, they are more ideally suited for greenhouse cultivation.
Soil: A rich, organic potting soil is best for terrestrial specimens.

They can also be grown mounted on fern or wood, but plants grown in this manner must be watered daily.
Fertilizer: Feed with a weak liquid fertilizer throughout the growing season.

Propagation:

These plants grow by creeping rhizomes, so a healthy adult plant can be divided to get new specimens. After division, pot them up or mount them and provide lots of water, warmth and humidity to encourage new growth. They can also be propagated by spore.

Repotting:

Container-grown specimens should be repotted as needed, but not too often. They are valued for their creeping and spreading habitat, so a plant cascading over a container is a beautiful thing and not always a reason to rush to repot the plant. Epiphytic plants should not be disturbed once the plant has attached to its substrate. You can take pieces of epiphytic plants to propagate new specimens.

Varieties:

Overall, there are about 40 species of Microsorum spread throughout the tropics in Africa, Asia and Australia. In their native environment, these are often seen growing alongside streams or in other wet, almost boggy areas. They freely scramble up and over rocks, up rocky faces, and up tree trunks. There are two main species found in cultivation:

• M. musifolium. Sometimes called the crocodile or alligator fern because of its distinctive scaly leaf texture, this plant is also known as Polypodium musifolium. The fronds are straplike and narrow, reaching 2-3 feet. This is a wonderful epiphytic plant.
• M. punctatum. This is a somewhat larger plant, with stalkless fronds that can reach 4 feet in length, with a pale yellow cast. These are either terrestrial or epiphytic, but probably best left to the greenhouse.

Grower's Tips:

The key with these plants is to provide adequate moisture and humidity, especially for older specimens that have escaped their container or fully epiphytic specimens. Many temperate growers will find these plants a challenge to keep alive over the long-term. In warmer climates, usually considered zone 10 or higher, they can be successfully grown out doors all season. Microsorum are vulnerable to pests including aphids, mealy bugs, scale, and white fly. If possible, identify the infestation as early as possible and treat with the least toxic option.